Does Anyone Care About Tin Whiskers Anymore?

Posted by Craig Hillman on Feb 23, 2017 9:23:00 AM

tin-whiskers.jpgAnyone remember tin whiskers? The destroyers of all that is good and just with electronic hardware?

Tin whiskers, small metallic filaments that grow from tin-based platings, have been a known entity since Compton (Corrosion Journal, 1951) and Herring (Physical Review, 1952) reported their appearance in early 1950’s. While irrelevant oddities for the structural world, these little conductive strands can be real killers for small scale microelectronics if not mitigated. Turns out, the simple solution was to add just a tiny bit of lead (Pb) (only 1%, but specs were written for 3% to provide some margin). And that’s what the world did.

With the move to Pb-free beginning in 2000 driven by RoHS, loud and repeated warnings of doom and gloom were thrust upon the marketplace. Specific organizations proclaimed massive failures due to tin whiskers if Pb-free were to move forward.

Seventeen years later (let me repeat that: SEVENTEEN years), what happened? Pretty much, nothing. The failure rate of electronics is not noticeably different before and after RoHS. And tin whiskers are not the root-cause of a significant portion of field failures (sorry, tin whiskers did not cause the Toyota sudden-acceleration problem).

So what did happen? Two things. One: motivation. When you produce BILLIONS of devices per year, you are highly motivated to prevent failures. Especially ones that are easy to prevent. Two: communication. When the tin plating formulations that do not cause whiskers were conclusively formulated, the information was rapidly shared throughout the electronic parts supply chain. In the 12 years that DfR Solutions has been in business, all known tin whisker failures have come from non-standard parts like housings, bus bars, mechanical hardware, specialty connections, etc. — not a single one from commercial off-the-shelf leaded (SOIC, QFP, etc.) electronic devices.

You can see the results on the device manufacturers’ websites. For over 90% of them, all traces of tin whiskers (test protocols, mitigation methods, compliance to industry standards, etc.) have been wiped clean. Why talk about something that almost never happens?

Tin whiskers — or the lack of them — is a demonstration of reliability working like it is supposed to: work on the problem, fix the problem, move on to another problem. For additional information on mitigating risk and improving reliability, download our webinar, Suitability of Copper Wire Bonded ICs for Harsh Environment Electronic Applications. Click the button below for your free copy.

Suitability of Copper Wire Bonded ICs Webinar

Topics: Design for Reliability

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